Types of Alarms in Distributed Control System (DCS)

Here, the different warning types used in the Distributed Control System (DCS) and Programmable Logic Controllers (PLC) are discussed.

Types of Alarms:

Process Alarms

Such alarms may be related to system efficiency or suggest equipment defects. This form of alarm is typically integrated into the system of control (usually a DCS) and uses the same sensors as the system of control.

Machinery or Equipment Alarms

Such warnings help detect equipment issues and do not directly affect the system operation.

Safety Related Alarms:

Such warnings are used to alert operators to a situation that may be dangerous or detrimental to the plant.

Such alarms should normally have a high priority and should be independent of the devices they monitor when they are involved in protecting against malfunction by the control system. In many instances, the security shutdown mechanism itself produces such warnings.

Shutdown Alarms

This type of alarm informs the operator that the SIS has reached and triggered an automatic shutdown case. It must be recalled, however, that shutdowns will not occur in all alarm systems. There are situations where the consequence of automatic start-up is such alarms.

The device would enable the stand-by generator to power up in the event of a power failure. Another example is the stand-by pump auto-start when the main system is going down. For a K.O. sour air, an on - off pump is installed. Beat, beat.

When the water level in the drum is high, the pump will start and stop when the water level is low. There are warnings that suggest a high or low level of water. It’s a pump.

Other alarm systems: the separate hardwire announcer system could incorporate the following alarms in addition to critical process safety alarms:

  • Fire (e.g. Satellite Instrument House)
  • Spill or toxic release
  • Safety shower
  • Power system fault
  • Electrical room or Substation smoke detector
  • Ventilation failure